Did you know?

Click any word in a definition or example to find the entry for that word

brain - definition and synonyms


What are red words?

90% of the time, speakers of English use just 7,500 words in speech and writing. These words appear in red, and are graded with stars. One-star words are frequent, two-star words are more frequent, and three-star words are the most frequent.



The thesaurus of synonyms and related words is fully integrated into the dictionary. Click on the thesaurus category heading under the button in an entry to see the synonyms and related words for that meaning.

noun brain pronunciation in British English /breɪn/
Word Forms
  • Facebook
  • Twitter
  1. 1
    [countable] the organ inside your head that allows you to think and feel, and controls your body
    The human brain is divided into two halves.
    The illness had affected his brain.
    1. a.
      [only before noun] belonging to or connected with the brain
      a brain tumour/scan/operation
      brain activity/function
    2. b.


      [plural] the brain of an animal cooked and eaten as food
      Synonyms and related words
  2. 2
    [countable] [often plural] mental ability or intelligence
    She felt that she could almost see his brain working.
    You have to use your brains in this job.
    have brains/a brain (=be intelligent): He’s good-looking, and he’s got brains.
    1. a.
      [countable] an intelligent person
      The best brains in the country have failed to solve this problem.



a course of study which is much shorter than a university course and focuses on the skills you need for a job, especially computer-related skills

BuzzWord Article

Open Dictionary


an ancient Roman system of underfloor heating, used to heat houses with hot air; from the Latin 'hypocaustum'

add a word


A must for anyone with an interest in the changing face of language. The Macmillan Dictionary blog explores English as it is spoken around the world today.

global English and language change from our blog